Decaborane, also called decaborane(14), is the

borane Trihydridoboron, also known as borane or borine, is an unstable and highly reactive molecule with the chemical formula . The preparation of borane carbonyl, BH3(CO), played an important role in exploring the chemistry of boranes, as it indicate ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

B₁₀ H₁₄. This white crystalline compound is one of the principal boron hydride clusters, both as a reference structure and as a precursor to other boron hydrides. It is toxic and volatile, with a foul odor.

Handling, properties and structure

The physical characteristics of decaborane(14) resemble those of

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromati ...

and

anthracene Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C14H10, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the production of the red dye alizarin and other dyes. Anthracene is colo ...

, all three of which are volatile colorless solids. Sublimation is the common method of purification. Decaborane is highly flammable, but, like other

boron hydrides Boranes is the name given to compounds with the formula BxHy and related anions. Many such boranes are known. Most common are those with 1 to 12 boron atoms. Although they have few practical applications, the boranes exhibit structures and bond ...

, it burns with a bright green flame. It is not sensitive to moist air, although it hydrolyzes in boiling water, releasing hydrogen and giving a solution of

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves ...

. It is soluble in cold water as well as a variety of non-polar and moderately polar

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

s. In decaborane, the B₁₀ framework resembles an incomplete octadecahedron. Each boron has one "radial" hydride, and four boron atoms near the open part of the cluster feature extra hydrides. In the language of cluster chemistry, the structure is classified as "nido".

Synthesis and reactions

It is commonly synthesized via the

pyrolysis The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''pyr ...

of smaller boron hydride clusters. For example, pyrolysis of B₂H₆ or B₅H₉ gives decaborane, with loss of H₂. On a laboratory scale, sodium borohydride is treated with boron trifluoride to give NaB₁₁H₁₄, which is acidified to release borane and hydrogen gas.Gary B. Dunks, Kathy Palmer-Ordonez, Eddie Hedaya "Decaborane(14)" Inorg. Synth. 1983, vol. 22, pp. 202–207. It reacts with Lewis bases (L) such as CH₃CN and Et₂S, to form adducts: :B₁₀H₁₄ + 2 L → B₁₀H₁₂L₂ + H₂ These species, which are classified as "arachno" clusters, in turn react with

acetylene Acetylene ( systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure ...

to give the "closo"

ortho-carborane Ortho-carborane is the organoboron compound with the formula C2B10H12. The prefix ''ortho'' is derived from ortho. It is the most prominent carborane. This derivative has been considered for a wide range of applications from heat-resistant polyme ...

: :B₁₀H₁₂·2L + C₂H₂ → C₂B₁₀H₁₂ + 2 L + H₂ Decaborane(14) is a weak Brønsted acid. Monodeprotonation generates the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

₁₀H₁₃sup>−, with again a nido structure. In the Brellochs reaction, decaborane is converted to arachno-CB₉H₁₄⁻: :B₁₀H₁₄ + CH₂O + 2 OH⁻ + H₂O → CB₉H₁₄⁻ + B(OH)₄⁻ + H₂

Applications

Decaborane has no significant applications, although the compound has often been investigated. In 2018, LPP Fusion announced plans for using decaborane in its next round of fusion experiments. Decaborane has been assessed for low energy

ion implantation Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fa ...

of boron in the manufacture of

semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

s. It has also been considered for plasma-assisted

chemical vapor deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (subst ...

for the manufacture of boron-containing

thin film A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many a ...

s. In fusion research, the

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beha ...

-absorbing nature of boron has led to the use of these thin boron-rich films to "boronize" the walls of the

tokamak A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma in the shape of a torus. The tokamak is one of several types of magnetic confinement devices being d ...

vacuum vessel to reduce recycling of particles and impurities into the plasma and improve overall performance. Decaborane was also developed as an additive to special high-performance

rocket fuel Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical ...

s. Its derivates were investigated as well, e.g. ethyl decaborane. Decaborane is an effective reagent for the

reductive amination Reductive amination (also known as reductive alkylation) is a form of amination that involves the conversion of a carbonyl group to an amine via an intermediate imine. The carbonyl group is most commonly a ketone or an aldehyde. It is considered t ...

of ketones and aldehydes.

Safety

Decaborane, like pentaborane, is a powerful toxin affecting the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all pa ...

, although decaborane is less toxic than pentaborane. It can be absorbed through skin. Purification by sublimation require a dynamic vacuum to remove evolved gases. Crude samples explode near 100 °C. It forms an explosive mixture with

carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemic ...

, which caused an often-mentioned explosion in a manufacturing facility.

Handling, properties and structure

Synthesis and reactions

Applications

Safety

References

Further reading